NFS: Improve legacy idmapping fallback

Fallback should happen only when the request_key() call fails, because
this indicates that there was a problem running the nfsidmap program.
We shouldn't call the legacy code if the error was elsewhere.

Signed-off-by: Bryan Schumaker <bjschuma@netappp.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

1 files changed, 26 insertions, 30 deletions

diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index c516da5873fd..c2c4163d5683 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -262,29 +262,42 @@ static ssize_t nfs_idmap_get_desc(const char *name, size_t namelen,
         return desclen;
 }
 
-static ssize_t nfs_idmap_request_key(struct key_type *key_type,
-                                     const char *name, size_t namelen,
-                                     const char *type, void *data,
-                                     size_t data_size, struct idmap *idmap)
+static struct key *nfs_idmap_request_key(const char *name, size_t namelen,
+                                         const char *type, struct idmap *idmap)
 {
-        const struct cred *saved_cred;
-        struct key *rkey;
         char *desc;
-        struct user_key_payload *payload;
+        struct key *rkey;
         ssize_t ret;
 
         ret = nfs_idmap_get_desc(name, namelen, type, strlen(type), &desc);
         if (ret <= 0)
-                goto out;
+                return ERR_PTR(ret);
+
+        rkey = request_key(&key_type_id_resolver, desc, "");
+        if (IS_ERR(rkey)) {
+                mutex_lock(&idmap->idmap_mutex);
+                rkey = request_key_with_auxdata(&key_type_id_resolver_legacy,
+                                                desc, "", 0, idmap);
+                mutex_unlock(&idmap->idmap_mutex);
+        }
+
+        kfree(desc);
+        return rkey;
+}
+
+static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
+                                 const char *type, void *data,
+                                 size_t data_size, struct idmap *idmap)
+{
+        const struct cred *saved_cred;
+        struct key *rkey;
+        struct user_key_payload *payload;
+        ssize_t ret;
 
         saved_cred = override_creds(id_resolver_cache);
-        if (idmap)
-                rkey = request_key_with_auxdata(key_type, desc, "", 0, idmap);
-        else
-                rkey = request_key(&key_type_id_resolver, desc, "");
+        rkey = nfs_idmap_request_key(name, namelen, type, idmap);
         revert_creds(saved_cred);
 
-        kfree(desc);
         if (IS_ERR(rkey)) {
                 ret = PTR_ERR(rkey);
                 goto out;
@@ -316,23 +329,6 @@ out:
         return ret;
 }
 
-static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
-                                 const char *type, void *data,
-                                 size_t data_size, struct idmap *idmap)
-{
-        ssize_t ret = nfs_idmap_request_key(&key_type_id_resolver,
-                                            name, namelen, type, data,
-                                            data_size, NULL);
-        if (ret < 0) {
-                mutex_lock(&idmap->idmap_mutex);
-                ret = nfs_idmap_request_key(&key_type_id_resolver_legacy,
-                                            name, namelen, type, data,
-                                            data_size, idmap);
-                mutex_unlock(&idmap->idmap_mutex);
-        }
-        return ret;
-}
-
 /* ID -> Name */
 static ssize_t nfs_idmap_lookup_name(__u32 id, const char *type, char *buf,
                                      size_t buflen, struct idmap *idmap)